/*
 * This project provides a number of implementations for indexing and evaluating
 * <i>Continuous Top-k Queries over Text Streams</i>
 * and has been developped as part of the work described in the article:
 * 
 * Vouzoukidou, N., Amann, B., & Christophides, V. (2012, October). 
 * Processing continuous text queries featuring non-homogeneous scoring functions.
 * In Proceedings of the 21st ACM international conference on Information and 
 * knowledge management (pp. 1065-1074). ACM.
 * http://dl.acm.org/citation.cfm?id=2398404
 * 
 * This software is distributed under the GNU General Public License and as an
 * additional condition of usage, please cite the aforementioned article.
 * 
 * Copyright (C) 2012 ICS/FORTH, Greece and 
 *               2012 LIP6, France
 * 
 * Author: Vouzoukidou Nelly, email: nelly.vouzoukidou (at) gmail (dot) com
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package gr.forth.ics.continuoustopk.index;

import gr.forth.ics.continuoustopk.Item;
import gr.forth.ics.continuoustopk.Query;
import gr.forth.ics.continuoustopk.Term;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * A naive implementation of a query index. Maps each term to the list of queries it contains them.
 *
 * <p>This implementation should be used for correctness testing and
 * experimental purposes only.</p>
 * 
 * @author Vouzoukidou Nelly, email: nelly.vouzoukidou (at) gmail (dot) com
 */
public class SimpleQueryIndex extends AbstractQueryIndex {
    private Map<Term, List<Query>> map;

    public SimpleQueryIndex() {
        map = new HashMap<Term, List<Query>>();
    }

    public void add(Query query) {
        for (Term term : query) {
            List<Query> queryList = map.get(term);
            if (queryList == null) {
                queryList = new ArrayList<Query>();
                map.put(term, queryList);
            }
            queryList.add(query);
        }
    }

    protected void matchItem(Item item) {
        for (Term term : item) {
            List<Query> queryList = map.get(term);
            if (queryList == null) {
                continue;
            }
            // optimized for the ArrayList: This format has a much faster performance than the
            // "for (Query query : queryList)" statement
            for (int i = 0; i < queryList.size(); i++) {
                match(queryList.get(i), item, term, 0);
            }
        }
    }

    public Iterable<Query> queries(Term term) {
        return map.get(term);
    }

    public void clear() {
        map.clear();
    }

    public Iterator<Term> terms() {
        return map.keySet().iterator();
    }

    public int queryCount(Term term) {
        return map.get(term).size();
    }
}
